The present invention relates to a system for non-destructively acquiring and processing information about a test piece in real time. The system has particular application in non-destructive ultrasonic inspection of test pieces such as railroad rails. However, the system may be used to acquire and process information in real time derived from arrays of ultrasonic transducers designed to inspect other types of test pieces.
Various systems for ultrasonically inspecting test pieces are presently known. Such a system for testing a railroad rail is disclosed in U.S. Pat. No. 4,165,648 (Pagano) and includes leading and trailing ultrasonic inspection wheels adapted to roll on a railroad rail in spaced relation. An array of ultrasonic transducers is mounted in each inspection wheel and includes two transducers looking laterally of the rail, three transducers looking longitudinally, one transducer looking normally and one send/receiver transducer. The send/receive transducer in the leading wheel operates in cooperation with the similar transducer in the trailing wheel to transmit ultrasonic energy thereto and receive ultrasonic energy therefrom in an alternating send/receive mode. Each of the transducers in the leading and trailing wheels is independently capable of transmitting ultrasonic energy, through a suitable coupling medium in the wheel, into the rail and of receiving ultrasonic energy transmitted back thereto to produce an individual response signal. Each response signal is capable of indicating anomolies in the rail, be they expected or unexpected, by indicating if ultrasonic energy has been deflected away from or attenuated in transit to an energy receiving transducer. Expected rail anomolies include joints in welded rails and bolt holes. Unexpected anomolies in rails include vertical split head and bolt hole enlargement defects. The type of anomoly detected may be classified at least in part by noting the transducers in the array which produced and received the energy indicating the anomoly. For example, vertical split head and rail defects are detected by energy produced and received by the laterally looking transducers in the apparatus described above.
While the wheels are rolled along the rail, the transducers are energized or pulsed in a known sequence selected to minimize interference from other transducers operative in the system and are subsequently monitored, also in a known sequence, to produce a set of response signals representing the ultrasonic inspection of the rail. It is apparent, then, that the transducer arrays produce a large volume of information in short periods of time, particularly when the inspection wheels are moved rapidly over the rail.
It is desirable to process and classify the large volume of information derived from such rail inspection apparatus in real time, that is, as the information is being collected or acquired. However, in the past, problems have been encountered in designing support systems for acquiring and analyzing information with the desired rapidity. One limiting factor, which in the past has prevented real time processing and analysis, is the time required for the system to make an information classification decision. The rate at which information is collected and, hence, the desired information input rate is not compatible with the rate at which the support system can process the information. Furthermore, simply too much information may be produced for the support system to digest. Therefore, two stage classification processes have been developed wherein information is collected in a first stage and classified and analyzed in non-real time in a second stage. However, such two-stage systems have disadvantages.